If your opponent possesses at least 1 monster, you can Special Summon Earth Armor Ninja from your hand, and Normal Summon Masked Ninja Ebisu, trigger Ebisu’s effect to return 2 Spell/Trap cards from your opponent’s field back to their hand.
These are the range of popular Ninjitsu cards that are used in most Ninja decks. Ninjitsu Art of Transformation will exchange your targeted Ninja monster with another Ninja monster that is less than or equal to the level of the monster + 3. Ninjitsu Art of Duplication can exchange your targeted Ninja monster with any number of Ninja monsters with combined levels less than or equal to the level of the tributed Ninja monster. Ninjitsu Art of Shadow Sealing tributes 1 of your Ninja monster to banish 1 monster your opponent controls, and that monster card zone cannot be used. Ninjitsu Art Notebook allows you to discard 1 Ninja monster to set 1 Ninjitsu Art Spell/Trap from your deck, except Ninjitsu Art Notebook. Armor Ninjitsu Art of Alchemy destroys all face-up Ninjitsu Art cards you control and allows you to draw 2 cards.